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B s signal selection

B s signal selection. Donatella Lucchesi University and INFN Padova for B s Mixing group. CDF Collaboration Meeting June 7, 2006. The Blessed Selections: hadronic decays. Signal B s D s  D s . B s D s  D s  KK D s K *0 K K *0 K D s 3 B s D s 3

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B s signal selection

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  1. Bs signal selection Donatella Lucchesi University and INFN Padova for Bs Mixing group CDF Collaboration Meeting June 7, 2006

  2. The Blessed Selections: hadronic decays Signal BsDs Ds  BsDs Ds  KK Ds K*0K K*0 K Ds 3 BsDs3 Ds  Ds K*0K Partially reconstructed B mesons B0D- Combinatorial background Donatella Lucchesi

  3. Hadronic Bs decays summary B+D0 ~ 26,000 B0D- ~ 22,000 Donatella Lucchesi

  4. Blessed selection Bs semileptonic Decays BsDslX Ds  KK Ds K*0K K*0 K Ds 3 Total yield: Dsl ~37,000 events Donatella Lucchesi

  5. What can we do to improve it? • Include PID in the selection • Use NN to discriminate signal from background • Add new decay modes Donatella Lucchesi

  6. Including PID in the selections BsDs Ds K*0K K*0 K has reflection from B0D D Kpp when you give K mass to p Standard analysis use D+ veto: |MKpp – MD+|>24 MeV A. Heijboer Donatella Lucchesi

  7. Including PID in the selections Aart proposal: |MKpp – MD+|>18 MeV OR CCL0 19.223.0 Give this to NN A. Heijboer J. Mulmestadt Johannes idea: LR cut event by event increases Ds 1640 In progress the Bs significance evaluation Donatella Lucchesi

  8. Neural Network selections B. Casal, K. Anikeev Use ROOTSNNS v3.0 • Train NN to separate signal from bckg (side bands) • Optimize to maximize • Fit mass distribution using the actual mixing fitter Rectangular cuts NN cuts Increase 33% like adding 78% of more data Donatella Lucchesi

  9. Neural Network selections summary B. Casal, K. Anikeev 57.78/43.30=1.3 improvement A Use wrong charge events as background in the future? Donatella Lucchesi

  10. Partially Reconstructed B Jeff Miles BD, D*p ++0 , D*Dg/p0 treated as hadronic? • Large yields (same order of fully reconstructed) • High k-factor, lose soft g/p0 • Lower S/B Depend on mass Different K def. investigated finally use the standard one Donatella Lucchesi

  11. Partially Reconstructed B Amanda Deisher B0D* -[D0 -] + 5.00<mass<5.35 GeV/c2 Low combinatorial background ct2= 464.6 +14.2–13.5 mm Above 5.17 GeV D*p and D*K Donatella Lucchesi

  12. New Decay Modes Simone Pagan Griso BsDs Ds KsK Ks has reflection from B0D D 3p as for Ds K*0K K*0 K Different topology easy to separate ~270 events 1fb-1 Using PID 16% increase Donatella Lucchesi

  13. Semileptonic decay modes V. Tiwari, G. Gomez-Ceballos • Improve event selection including PID BsDslx: • Dsfp combinatorial bck reduce by factor 2 • Ds K*K yield increased by factor ~2.5 and combinatorial bck reduced by factor 2 • Include l+SVT dataset • Remove the ct* cut Noticeable gain Donatella Lucchesi

  14. Summary • The number of events can be increased by including • new decay modes, partially reconstructed events • and by optimizing cuts. • Plan for the summer: • Include partially reconstructed modes and optimize cuts. • The actual gain on Dms significance will be the • combination of all the effect. • Expected improvements on sA: • 1.3 for the hadronic decay modes cuts optimization • “Something” for semileptonic decays • Under evaluation for adding partially reconstructed • hadronic decay Donatella Lucchesi

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